As digital TV such as terrestrial broadcasting, satellite broadcasting, or IPTV becomes widely available, subscribers can watch clear video programs. Unlike analog broadcasting, video quality may be deteriorated while compressing video information in digital broadcasting. As high compression is applied, the video quality of decoded video signals may be degraded. The channel capacity in terrestrial broadcasting and satellite broadcasting is fixed so that the video quality depends only on video encoder performance. However, in IPTV, the channel capacity is not fixed, but may be extendable as necessary. Thus, the encoding bit rate of the content also affects the video quality of decoded signals. Furthermore, various error patterns may occur due to transmission errors.
If the broadcaster monitors video quality which may be perceived by a viewer and uses the results to produce or transmit the content, the broadcaster can build a more efficient broadcasting system and increase the client satisfaction. For this purpose, a method for measuring and evaluating video quality of digital TV is required. Presently, international standardization organizations are currently working on the standardization of objective methods to measure subjective video quality and these methods can be classified into three categories:
1) The full-reference (FR) method computes a similarity or a distortion difference between a source video sequence and a processed video sequence (PVS) to measure relative video quality. Therefore, a level of the processed video quality may be most accurately determined. However, since the receiving side needs a source video sequence which is used at the transmitting side, the application area of the FR method is very restricted.
2) The reduced-reference (RR) method extracts and compares features from the source video sequence and the processed video sequence to measure relative video quality. Therefore, the relative video quality may be measured with a smaller amount of calculation compared with the FR method.
3) The no-reference (NR) method computes video quality only using the processed video sequence without using the source video sequence or feature information. However, the NR method is least accurate since no reference video sequence is used.
However, since the existing video quality measuring methods receive video data, decode the received video data, and then evaluate video quality using the decoded video data, the quality measurement performance is limited and the processing time is rather long.